[Plugin: Pinterest "Pin It" Button] Images not showing up

I installed the plugin, and everything works fine, except that when you click the “pin it” button a new window pops up and you are supposed to select the image to pin, but all the images are blank. You can still click on the blank images and it will open up the next window and show the actual image, but it’s that first screen where you select the image that it’s not showing up. Is there something I did wrong? Or is this a bug? Thanks for your help!